Method for treating hydrocarbon producing formations



' 4vf; vri R-EISTLE, JR l METHOD FOR TRATING HYDRocARBbnvPP-onucmc FORMATIONS Y Filed Jan. 6, 195s fueran/Nd NAN l v 'lm/Enron. Carl E. @sisi/e,-

` such A 2,169,491f3] j l lvm/THOD FOR TREATING HYDROCARBDN 1 -,L rnoDUcrNG ronMArroNs Carl 13'..y Reis'tle, Jr., Houston,`1`ex., assigner, by mesne assignments to Esso Research andEngneariug Com- ,-.pany, Elisabeth, N. J., a corporation of Delaware reputation autres, 1955,52@ 'N0-"480,209 l :schim-j- (CL 1766-42) increasing the permeability of a plurality of hydrocarbon /productive intervals.

A ln its more specific aspects, the invention has to do with selectively united stagnantr i vtion economically attractive. As pointed out, increasing i the permeability or productivityof the hydrocarbon-c'outaining strata by stimulating methodssuch as 'by 'frasi'A '..Tbe present-invention -may. be briey described as a method for selectively 'increasing the permeability or productivity of a plurality of hydrocarbon productive intervals penetrated by a well borel Briefly, the invention involves perforating a rst hydrocarbon productive interval penetrated by a well bore to open up th'e first hydrocarbon productive interval into the well bore. The perforated in- `terval is then isolated from the remaincr of the fell vbore andthe perforated interval is then treated by contacting same with a reagent to increase the permeability or productivity of the perforated first interval.Y Thereafter, a second hydrocarbon productive interval which4 may be vertically spaced from the rst hydrocarbon productive interval is perforated and then isolated from the4 remainder of the well bore. The isolated second productive interval after perforation is then treated by contacting saine with a reagent -to increase the permeability 'or pro ductivity of the isolated perforated second interval.

I The permeability o r productivity of the perforated inteivals may be increased preferably by contacting same with a fracturing lluid under pressure suflicient to fracture rrr" the formation whereby the permeability or productivity of i the formation is increased.' The permeability or 'productivity of the isolated intervals may be increased also by treatment with acid, hydrocarbon under pressure, or by treatment withan acid gel, a water gel or a hydrocarbon gel. .j 'v *Y When a f ractring lluid is used, this fracturing fluid may suitably be a` hydrocarbon, which may be crude petroleum, kerosene, acid gel; and the like, and Amay contain-bodying agents and/or propping agents, such as of the nature of sand and the like, to lodge in crevces and cracks lformed by the high pressure treatment to main`v tain the crevices or cracks open to allow oil to drain and/or be produced from the well bore.

The present invention is particularly applicable in wcll bores having a casing arranged therein which penetrates a plurality of hydrocarbon productive intervals, formations,

"""'zones or strata. Frequently the oil-productive intervals overlie one another and may beiseparated by non -productive intervals. When'onventional treatment is em val less resistant to treatment has had its permeability or productivity increased while those less susceptible to4 the treatment were not increased in permeability 4or prod iic- Onezone would be treated atthe expense'of Y. easily therethrough.

turing treatment or b'y acidizing, has resulted in the fori mations or strata which are structurally weakest or rea =l tive with the acid to be treated where the formations that are structurally strongest or less reactive with the acid to resist the treatment' and not respond as much as those treated in the. past only one of a plurality of intervals has responded as the rest of the hydrocarbon productive in#` te'rvals have had no effective treatment given thereto..1 In accordance with the presen-t invention, anyone or all of a desired number of hydrocarbon productive inter-V lvals may betreated or fractured for simultaneous or see' quential production of hydrocarbons by increasing the trated by a well bore is possible without making it neces-gv sary to kill the well and 'avoiding round trips .into the well.

The present invention will-be more completely invention.

Referring now to the drawing and particularly to Fig. 1,'

a well bore 11 has been drilled from the eartli's surface` l12 to penetrate a plurality of intervals 13, 14, 15 of which intervals 13 and 1.5 are hydrocarbon productive.

The wellbore 1 1 has a casing 16 arranged 'therein and cemented in .place with primary cement 17.v Run into the casing through a wellhead arrangement 18 is' a tubing string 19 which has arranged on its lower 'end a .packer 20 which wil1-resist 'flow downwardly in the annulus A I between the casing 16 and the tubing 19 but will allow', f

llow upwardly past the packer 20. Carried on the-lower end 21 of the tubing 19 is a casing burr remover 22 which is designed to remove burrs and obstructions from the in' terior wall of casing .16. The tubing 19 is provided with a lubricator 23 to allow running into the tubing 1.9 and lowering therethrough on a wire line 24 a gunperforator.

25 which may be of the shaped charge or bullet gun type. i Y

In Fig. 1 .thej'gun perforator 25 yhas been lowered through the tubing 19 adjacent` the hydrocarbon produc- It will be notcd'that vcommu nication is had to the' i annulus A by means of a conduit 28 controlled hy.. a va1ve29.` .t I

Referring now to Fig. 2, the tubing 19 carrying the packer 20 and the burr remover 22 is then'manipulatn'l s in the casing'l downwardly, such that the burr remover 22 lremoves all burrs and ,protuberances from the interior wall of-the casing 16 such'that the As shown more clearly the well bore, the=burr remover 22 having been carried.

' ployed for the plurality of intervals heretofore the inter;

downwardly in the casing to provide a free smooth path:

which serve to increase the permeability or 'pi'txluctiv ityl f of. the hydrocarbon productive interval 15. 'Ihe tl'ot'v packer 20 may slidej in 'Fi-g. vsj inspecteren arranged below the ,perforated interval to `isolate the; lower portion of the casing 1'6 fromthe remainder of of thefract'uring Huid or treating reagentis as indicatedn Referring now to'fg. after'theipressure has beeni exerted on the interval for a'sultic'ient length of time tol form the fractures 28, uid pressure is released from the annulus A by opening the valve 29.l Thereafter,

the tubing 19 is raised again in the casing 16 until the packing member 2() and the burr remover 22 are above the hydrocarbon productive interval 13. The gun per-- forator attached to wire line 24v is lowered again through the lubricator' 2 -3 until the gun perforator 25 is adjacent hydrocarbon productive interval 13. The gu'n perfotator 25 is operated to form perforations ,27 through the casing 16. and primary cement 17' and to penetrate thehydrocarbon productive interval 13.

The gun pcrfrator 25 is then withdrawn by reeling in the wire line 24 and removing same from tubing 19 lful in well treating and stimulating operations in that through lubricator 23. As sho'wn more clearly in Piu.

5, the tubing 19 is then lowered in the casing 16 such that the burr remover 22 may form a smooth surface `for the packer 20 in the perforated interval 13 of the casing 16'. The tubing is then lowered until the lower end 21 thereof is below the perforated interval 13 such that the packer 20 isolates the perforated interval 13Y from the remainder of the well casing 15. The valve 29 'in conduit 38 is then opened and a treating reagent,

` such as a fracturing fluid, Ais introduced into the casing annulus A and a sufficient amount of pressure to crack I the interval 13 is imposed on the interval 13 through ``the perforations 29 in the well casing 16 to form lateral and vertical c'revicesorl cracks or fractures 30 in the interval 13. After the pressure has been supplied a s utlicient amount of time to crack or fracture' the interval 13 as indicated by a decrease of the pufnp pres' sure, the pr`essu re is then relievedon the annulus A. The tubing 19 is then raised to a position as shown in Fig. 7 so that the lower open end 21 is above the fracthe tubing.

turedv interval 13. l Production of o il and/or gas may f Thus, it is contemplated that the production of hydrocarbons may be had either simultaneously or sequentially from a plurality of treated hydrocarbon intervals. For example, it may be desirable to obtairt productionsimultancously from intervals 13 and 1 5 or vit may bc des irable to obtain production first from interval 15 by placing the open end 21 of the tubing above the interval 15 and closing off the casing-tubing annulus A and allowing production to be had into the casing 16 land thence upwardly to the tubing 19 or it may be desirable to isolate. the treated formation 1S by replacing the packer 20 with a downwardly facing .cup packer which will serve to isolate the annulus below the interval 13 and, then .hydrocarbon productive interval, scaling uff' the annulus productive interval,` sealing .olf the annulus between said forated second interval. v

by closing offthe tubing 19, production may be had up the annulus A from the interval 13.

It iswirhin thc purview of the present invention tol increase the permeability or productivity of the formation, zones, intervals, stratum and the like by treatment with acid, acid gel, gellcd water, hydrocarbonor hydro.

carbon-containing bodying agent such that the formation ermeability or productivity is increased by "physical cracking or fracturing of the formation or by reactionl I Vtioned above aseeond 'productive interval, and then drocarbons' and' the like." For-example, .permeability of a plurality of hydrocarbon productive intervals-pene'- downward fluid flow therethrough and then imposing-fluid or productivity of the formations or zones may be increased and well stimulation practiced by introducing hydrocarbons, 35.- or water into the interval whose permeability or productivity has beeni-ncreased in accord-V ance with the present invention. v v It may be seen that the present invention vis 'quite uscthe permeability or productivity of a plurality of hydrocarbon Aproductive intervals may be increased and p'roduction then had from the so-treated intervals by providing a pressure differential into the well bore. such that hydrocarbons are flowed therein. I The invention is of great utility in that perforation, isolation and fracturing or treating of cach individual stratum in a plurality of strata may be performed with. .out requiring withdrawing of the tubing from the well The nature and objects of the present invent-ion havivxlg"`"- been completely described' and illustrated, what I wish'to claim as new and useful and -to secure by Letters Patents:

. l. A method for selectively increasing the permeability of a plurality of hydrocarbon productive intervals penetrated by a well bore having a tubing arranged therein .V

which comprises perforating a first hydrocarbon productive interval, sealing olf the annulus between said tubing e and said well bore below said productive interval, imposing uid pressure on said perforated first interval sufficient to fracture said first interval perforating a second between said tubing and sa-id well bore beldw. said second productive interval a-nd then imposing-duid pressure on said second perforated interval sufficient toLgaeture said second interval. Y, 2. A method for selectively increasing the permeability trated. by a cased'well -borc having a' tubing arranged therein which comprises perforating a first-hydrocarbon tubing and said casing below said first productive interval from downward fluid flow therethrough, imposing fluid pressure in said annulus sufficient to fracturesaid first interval, perforating a secondhydrocarbon productive interval,'sealing ofi the annulus between said tubing and said casing below said second productive, interval frompressure in said annulus sufficient to fracture ps aid-'per- 3. A method for selectively increasing the p ern'teability4 of a plurality of hydrocarbon productive intervals penetrated by a well bore having a tubing arranged therein provided with packing means adapted to seal olf the an-l nulus between said tubing and said well bore. adiaccnt,` its lower open end which comprises positioning the lower ope'n end of said tubing above a first productive interval;l lowering a wireline perforator through said tubing to adjacentsad interval, perforating said first interval, ree moving" -said perforator through said tubing,lowering saidb tubing until said packer is positioned rbelow said. lirst itxterval, imposing .fluid lpressurein said annulus sufi'cent to fracture saidlirst interval, relieving sala' -tluid pressurefrom said annulusand then manipulating -said tubing von tically until the lower open end. of said tubing isposrepeating said above steps at said second interval.

4. A method for selectively increasing thepcrmcability t of a-plurality-of Hydrocarbon productive intervals penetrated by acased well' bore'having a-r tubing arranged ftherein provided with packing. xneans adapted to seal ot V the annulus between said tubing and said casing and burr removing means adapted to remove burrs from said perforated casing adjacent its lower open end which` com p rises positioning the lovver op'en end of said tubing above a rst 4productive interval, perforating said rst interval, lowering said tubing and therebv removing said .bjn'x'sl until said packer is positioned below said jrst interval, imposing fluid vpressure on said annulus suicient to frat:- ture said rst interval, manipulating said tubing vertically to position the lower open end thereof above a seoond productive interval, perforating said second produrr-v tive interval, lowering said tubing and thereby vremoving saidvburrs until said packer is positioned Y A below said set:- y ond 'productive interval and .then nft'posiug .fluid pressure on 'said annulus suici'ent to fracturesaid second produ@ tive interval.

References Cited lin thetile -ofthis 'patent UNITED STATES PATENTS 4 y 2,642,142 g Clark M June 16, 1953 lo 2,676,662 Ritzmann --A.--.. Apr. 27. 1954 2,693,854 Abendroth ..--L- Nov. 2, 1951! f orHER REFERENCES 1 A Hydra-olie Fracturing, copyright- 1954,1t`h'e Oil 'and Gas Journal, Tulsa, Qklahoma, pages 29 and-5S relied on; 

